Electromagnetic band gap structures

ABSTRACT

Devices for mitigating or stopping noise or surface current on a display are provided. An electronic device including a display may include a display substrate, a mid-support plate that is adjacent to the display substrate, and a lower support plate that is adjacent to the mid-support plate. A space exists between the mid-support plate and the lower support plate. The mid-support plate includes one or more electromagnetic band gap (EBG) structures formed through the mid-support plate, one or more electromagnetic band gap structures mounted onto the mid-support plate, or both. The one or more electromagnetic band gap structures may mitigate or stop surface current flow across the display.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 16/585,238, filed Sep. 27, 2019, entitled,“ELECTROMAGNETIC BANDGAP STRUCTURES,” the disclosure of which isincorporated by reference in its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to wireless devices and, moreparticularly, to radio frequency (RF) devices that include a lightemitting diode (LED) display or a liquid crystal display (LCD) with ametallic back plate in parallel with a single or multiple systemmetallic support plates.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Electronic devices, such as cellular phones and laptops, often includetransceivers to facilitate wireless communication of data, such as byeither transmitting or receiving wireless data signals, with otherelectronic devices. These data signals are typically communicated over anetwork channel on a frequency band to and from one or more wirelessdevices. By way of example, one electronic device may transmit datasignals to another electronic device over a channel of a particularWi-Fi frequency band (e.g., 2.4 Gigahertz (GHz) or 5 GHz) or a cellularfrequency band (e.g. 0.6 GHz to 3 GHz).

Electronic devices may include an electronic display, such as a lightemitting diode (LED) display, an organic light emitting diode (OLED)display, or a liquid crystal display (LCD), to present visualinformation. For example, an LED display includes multiple pixels, eachmade up of an array of LEDs. The display architecture may include adisplay substrate stacked on one or more metallic display platesseparated by an air gap. The display plates may include material used tofacilitate displaying images by the light emitted from the LEDs.Briefly, integrating the display in a device, such as by stacking thedisplay substrate on the metallic support plate(s) in parallel, maygenerate a transmission line effect due to the air gap between theconductive metallic support plates. The display substrate may includedisplay circuits, multiple data lines (e.g., thousands of data linescommunicating data between components on the display plate), and a glasssubstrate. In some display substrates, the various metal data lines maybe located close to each other, thereby forming a plate-like structure.As such, and similar to the LED parallel support plates, a transmissionline effect may be created between the plate formed by the data linesand the support plate.

The “transmission line” may carry noise by allowing surface current toflow from one side of the device (e.g., on the display substrate) from anoise generator, which may be referred to as an “aggressor,” to theother side of the device to a component that may be adversely effectedby the noise, which may be referred to as the “victim.” The noise mayflow back-and-forth between the aggressor and the victim. In particular,the aggressor may include components of the device that are used fordevice operations not directly associated with an intended wirelesscommunication. For example, the aggressor may generally include displaymultiplexer and de-multiplexer circuits, diodes, microprocessors, chips,and the like.

On the other hand, the victim may include device components that areimpacted by the aggressor, such as components directly used for wirelesscommunication operations. The victim may include one or more antennas(e.g., Long-Term Evolution (LTE) antenna, global positioning system(GPS) antenna, and/or Wi-Fi antenna), low noise amplifier (LNA), poweramplifier (PA), etc. Unintended signals, voltage, or surface currentcausing noise may travel from the aggressor to the victim via thedisplay architecture, thereby impacting the intended wirelesscommunication signals. In some implementations, the aggressor may alsoinclude noise or surface current generated by a transmitted radiofrequency (RF) signal. For example, the noise occurring on the samefrequency band as the transmitted RF signal may couple to nonlineardisplay components or circuitry on the display substrate (e.g.multiplexer circuit), which may result in intermodulation of the noise.The intermodulated noise may occur on a receiver frequency band (ratherthan the transmitter frequency band) and may be coupled to the receiverthrough reflections. As such, the intermodulated noise may interferewith a victim, such as the receiver of the RF device.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

The present disclosure generally relates to mitigating or stopping noiseor surface current from flowing from one portion of an electrical deviceto another portion of the electrical device using one or moreelectromagnetic band gap structures (EBGs). In some embodiments, theelectromagnetic band gap structures may be etched into or mounted on andacross a support plate (e.g., mid-support plate) to create a stopbandfor surface current flowing across (e.g., back-and-forth) on the supportplate. Moreover, in some embodiments, the etched EBG structures may betuned to reduce or minimize surface current flow or other noiseoccurring at a particular frequency.

For example, the shape of the EBG structures etched across the supportplate may be tuned to avert the noise at particular frequencies. The EBGshapes may be characterized into two categories: narrowband andbroadband EBG shapes. Narrowband EBG shapes may be described by theirsimple structure and may be easily manufactured or etched inside aplate. By way of example, a rectangular slot shape design may beconsidered a narrowband EBG. Broadband EBG shapes may includemulti-edged shapes, such as a bow-tie shaped slot, which may be used totune for a range of frequencies using the length of the multiple edges(e.g., bow edge length and bow height edge length).

Various refinements of the features noted above may exist in relation tovarious aspects of the present disclosure. Further features may also beincorporated in these various aspects as well. These refinements andadditional features may exist individually or in any combination. Forinstance, various features discussed below in relation to one or more ofthe illustrated embodiments may be incorporated into any of theabove-described aspects of the present disclosure alone or in anycombination. The brief summary presented above is intended only tofamiliarize the reader with certain aspects and contexts of embodimentsof the present disclosure without limitation to the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a block diagram of an electronic device with a displayarchitecture that may include multiple display plates in parallel, inaccordance with an embodiment;

FIG. 2 is a front view of a handheld device representing an example ofthe electronic device of FIG. 1 , in accordance with an embodiment;

FIG. 3 is a front view of a handheld tablet device representing anotherexample of the electronic device of FIG. 1 , in accordance with anembodiment;

FIG. 4 is a front view and a side view of a wearable electronic devicerepresenting another example of the electronic device of FIG. 1 , inaccordance with an embodiment;

FIG. 5 is a diagram of EBG structures etched into and across a modifiedmid-support plate, in accordance with an embodiment;

FIG. 6 is a diagram of narrowband and broadband shaped EBG structuresused in the modified mid-support plate to avert noise occurring atparticular frequencies, in accordance with an embodiment;

FIG. 7 is a graph diagram of scattering parameter (S-parameter)performance for varying gap widths of EBG structures, in accordance withan embodiment;

FIG. 8 is a diagram of a slotted EBG structure formed through themodified mid-support plate, in accordance with an embodiment;

FIG. 9 is a diagram of a three dimensional EBG structure mounted ontothe modified mid-support plate, in accordance with an embodiment.

FIG. 10 is a diagram of multiple patterns of EBG structures etched intothe modified mid-support plate, and a radio frequency absorber placedbetween the mid-support plate and display substrate, in accordance withan embodiment.

FIG. 11 is a diagram of modified EBG structures of FIG. 10 based ondisplay features, in accordance with an embodiment; and

FIG. 12 is a diagram of multiple versions of the modified EBG structuresof FIG. 11 , in accordance with an embodiment.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

To improve wireless signal communication between wireless devices, asdiscussed above, embodiments presented herein describe EBG structuresetched across (e.g., defected ground structures (DGS)) or mounted acrossa support plate (e.g., mid-support plate) to avert or stop the surfacecurrent flowing from an aggressor component (e.g., noise generatingcomponent) to prevent it from impacting victim components (e.g.,component impacted by the aggressor). Additionally, depending on thefrequency band used for the wireless communications, the shape of theEBG structure may be modified (e.g., narrowband shape or broadbandshape) to prevent surface current interfering at a particular frequencyband (e.g., narrowband frequencies, such as those in the range of300-3400 hertz (Hz)) or a wide band of frequencies (e.g., broadbandfrequencies, such as those in the range of 50-7000 Hz). For example, ifsurface current is flowing from the aggressor to the victim when thedevice is communicating using Wi-Fi, such that the surface current isinterfering with multiple wireless signals communicated on the 2.4 GHzand 5.0 GHz frequency bands, then the EBG structures may be tuned toavert the surface current at 2.4 GHz and 5.0 GHz frequency bands.

With the foregoing in mind, a general description of a suitableelectronic device that may utilize a display with an array of slotsetched into its support plate will be provided below. Turning first toFIG. 1 , an electronic device 10 according to an embodiment of thepresent disclosure may include, among other things, one or moreprocessor(s) 12, memory 14, nonvolatile storage 16, a display 18, inputstructures 22, an input/output (I/O) interface 24, a network interface26, a transceiver 28, and a power source 30. The various functionalblocks shown in FIG. 1 may include hardware elements (includingcircuitry), software elements (including computer code stored on atangible computer-readable medium) or a combination of both hardware andsoftware elements. It should be noted that FIG. 1 is merely one exampleof a particular implementation and is intended to illustrate the typesof components that may be present in the electronic device 10.

By way of example, the electronic device 10 may represent a blockdiagram of the handheld mobile device depicted in FIG. 2 , the handheldtablet device depicted in FIG. 3 , the wearable electronic devicedepicted in FIG. 4 , or similar devices. It should be noted that theprocessor(s) 12 and other related items in FIG. 1 may be generallyreferred to herein as “data processing circuitry.” Such data processingcircuitry may be embodied wholly or in part as software, firmware,hardware, or any combination thereof. Furthermore, the data processingcircuitry may be a single contained processing module or may beincorporated wholly or partially within any of the other elements withinthe electronic device 10.

In the electronic device 10 of FIG. 1 , the processor(s) 12 may beoperably coupled with the memory 14 and the nonvolatile storage 16 tofacilitate the use of the processors(s) 12 to implement various storedalgorithms. The algorithms may include algorithms to control one or morecircuitry configurations (e.g., one or more antennas) to operate indifferent wireless communications, such as cellular, GPS, Wi-Fi, and thelike. Such programs or instructions executed by the processor(s) 12 maybe stored in any suitable article of manufacture that includes one ormore tangible, computer-readable media at least collectively storing theinstructions or routines, such as the memory 14 and the nonvolatilestorage 16. The memory 14 and the nonvolatile storage 16 may include anysuitable articles of manufacture for storing data and executableinstructions, such as random-access memory, read-only memory, rewritableflash memory, hard drives, and optical discs. In addition, programs(e.g., an operating system) encoded on such a computer program productmay also include instructions that may be executed by the processor(s)12 to enable the electronic device 10 to provide variousfunctionalities.

The input structures 22 of the electronic device 10 may enable a user tointeract with the electronic device 10 (e.g., pressing a button toincrease or decrease a volume level). The I/O interface 24 may enablethe electronic device 10 to interface with various other electronicdevices, as may the network interface 26. The network interface 26 mayinclude, for example, one or more interfaces for a personal area network(PAN), such as a Bluetooth network, for a local area network (LAN) orwireless local area network (WLAN), such as an 802.11x Wi-Fi network,and/or for a wide area network (WAN), such as a 3rd generation (3G)cellular network, 4th generation (4G) cellular network, long termevolution (LTE) cellular network, and long term evolution licenseassisted access (LTE-LAA) cellular network. The network interface 26 mayalso include one or more interfaces for, for example, broadband fixedwireless access networks (WiMAX), mobile broadband Wireless networks(mobile WiMAX), and so forth.

In certain embodiments, to allow the electronic device 10 to communicateover the aforementioned wireless networks (e.g., Wi-Fi, WiMAX, mobileWiMAX, 4G, LTE, and so forth), the electronic device 10 may include atransceiver 28. The transceiver 28 may include any circuitry that may beuseful in both wirelessly receiving and wirelessly transmitting signals(e.g., data signals). The transceiver 28 may include a transmitter and areceiver combined into a single unit. For example, the transceiver 28may transmit and receive orthogonal frequency-division multiplexing(OFDM) signals (e.g., OFDM data symbols) to support data communicationin wireless applications such as, but not limited to, PAN networks(e.g., Bluetooth), WLAN networks (e.g., 802.11x Wi-Fi), WAN networks(e.g., 3G, 4G, and LTE and LTE-LAA cellular networks), WiMAX networks,and mobile WiMAX networks.

As further illustrated, the electronic device 10 may include a powersource 30. The power source 30 may include any suitable source of power,such as a rechargeable lithium polymer (Li-poly) battery and/or analternating current (AC) power converter.

FIG. 2 depicts a front view of a handheld device 10A, which representsone embodiment of the electronic device 10. The handheld device 10A mayrepresent, for example, a portable phone, a media player, a personaldata organizer, a handheld game platform, or any combination of suchdevices. By way of example, the handheld device 10A may be a model of aniPhone® available from Apple Inc. of Cupertino, Calif. The handhelddevice 10A may include an enclosure 36 to protect interior componentsfrom physical damage and to shield them from electromagneticinterference. The enclosure 36 may surround the display 18. The I/Ointerfaces 24 may open through the enclosure 36 and may include, forexample, an I/O port for a hardwired connection for charging and/orcontent manipulation using a standard connector and protocol, such asthe Lightning connector provided by Apple Inc., a universal serial bus(USB), or other similar connector and protocol.

User input structures 22, in combination with the display 18, may allowa user to control the handheld device 10A. For example, the inputstructures 22 may activate or deactivate the handheld device 10A,navigate user interface to a home screen, a user-configurableapplication screen, and/or activate a voice-recognition feature of thehandheld device 10A. Other input structures 22 may provide volumecontrol or may toggle between vibrate and ring modes. Some inputstructures 22 may include a microphone that may obtain a user's voicefor various voice-related features and/or a speaker that may enableaudio playback. The input structures 22 may also include a headphoneinput that may provide a connection to external speakers and/orheadphones.

In certain embodiments, the electronic device 10 may take the form of aportable tablet electronic device, a wearable electronic device, orother type of electronic device. Such devices may include computers thatare generally portable (such as laptop, notebook, and tablet computers).In certain embodiments, the electronic device 10 in the form of acomputer may be a model of a MacBook®, MacBook® Pro, or MacBook Air®from Apple Inc.

By way of example, FIG. 3 depicts a front view of a handheld tabletdevice 10B, which represents another embodiment of the electronic device10. The handheld tablet device 10B may represent, for example, a tabletcomputer, or one of various portable computing devices. By way ofexample, the handheld tablet device 10B may be a tablet-sized embodimentof the electronic device 10, which may be, for example, a model of aniPad® available from Apple Inc. of Cupertino, Calif. The handheld tabletdevice 10B may also include an enclosure 36 that holds the electronicdisplay 18. Input structures 22 may include, for example, a hardware orvirtual home button. The I/O interfaces 24 may also open through theenclosure 36 and may include an I/O port for a hardwired connection forcharging and/or content manipulation.

Similarly, FIG. 4 depicts a wearable electronic device 10C representinganother embodiment of the electronic device 10 of FIG. 1 that may beusing the techniques described herein. By way of example, the wearableelectronic device 10C, which may include a wristband 43, may be an AppleWatch® by Apple Inc. More generally, the wearable electronic device 10Cmay be any wearable electronic device such as, for example, a wearableexercise monitoring device (e.g., pedometer, accelerometer, heart ratemonitor), or other device by another manufacturer. The wearableelectronic device 10C may also include an enclosure 36 that holds theelectronic display 18. The display 18 of the wearable electronic device10C may include a touch screen display 18 (e.g., light emitting diode(LED), organic light emitting diode (OLED) display, active-matrixorganic light emitting diode (AMOLED) display, liquid crystal display(LCD), and so forth), as well as input structures 22, which may allowusers to interact with a user interface of the wearable electronicdevice 10C.

As previously noted above, each embodiment (e.g., handheld device 10A,handheld tablet device 10B, and wearable electronic device 10C) of theelectronic device 10 may wirelessly communicate with other devices. Thearchitecture of the display 18 of the electronic devices 10 may includemultiple layers or plates in parallel, such as a display substrate ontop of two or more display plates, such as a mid-support plate and alower support plate (e.g., conductive display plates). The electronicdevice 10 may include EBG structures to mitigate surface current thatmay otherwise flow across the electronic device 10 due to the displayplates arranged in parallel. In particular, the EBG structures may be ona support plate, such as the mid-support plate, to avert the surfacecurrent, thereby mitigating interference with wireless signalstransmitted to or received by the electronic device 10.

As described herein, in certain implementations, the EBG structuresetched into the support plate may create a barrier to mitigate or stopthe surface current or noise from flowing across the device. In otherimplementations, the shape of the EBG structures may be adjusted to tuneto a narrowband frequency or broadband frequency by using selected andappropriate EBG structures, such that surface current is averted fornoise occurring on the tuned frequency or frequencies.

Although some of the following discussions relate to EBG structures onthe mid-support plate, which represents a particular embodiment, itshould be noted that the EBG structures may also implemented on thedisplay substrate and/or the lower support plate. As previouslydiscussed, surface current may flow from the “aggressor” to the “victim”of the electronic device 10 without the disclosed EBG structures on themid-support plate.

In particular, without the disclosed EBG structures on the mid-supportplate, the aggressor may include device components that impact theperformance of other device components used for intended deviceoperations, such as wireless communications. By way of example, theaggressor component may include, but is not limited to, displaymultiplexer and de-multiplexer circuits, diodes, chips, microprocessors,and the like. Without the disclosed EBG structures, the aggressorcomponents may result in surface current flowing from it to othercomponents of the device, the victim, which are used for the intendedwireless signals. By way of example, the victim component may includeone or more device antennas (e.g., Long-Term Evolution (LTE) antenna,GPS antenna, and/or Wi-Fi antenna), low noise amplifier (LNA), poweramplifier (PA), etc. The unintended surface current may flow from theaggressor to the victim, thereby impacting the intended wirelesscommunication signals, which may result in increased error rates and/orthe electronic device 10 consuming additional power to transmit and/orreceive the impacted wireless signals. Moreover, during some RFcommunications, the surface current may flow back-and-forth between theaggressor and the victim.

The mid-support plate without EBG structures may result in surfacecurrent that flows in both directions on the mid-support plate via thetransmission line effect. Such surface current propagation may occurwhen the transmission line effect is created by the air gap between themetal plate of the display substrate that is formed by dense data linesand the mid-support plate. The surface current may propagate from theaggressor to the victim, and then back to the aggressor. In someembodiments, EBG structures may mitigate noise caused by the one or moreaggressors. Additionally, the aggressor and/or the victim may change(e.g., to a different component) as the surface current flows in bothdirections.

By way of example, an electronic device 10 without the disclosed EBGstructures and operation on a particular RF frequency, may result innoise at the particular RF frequency that causes interference with thereceiver of the electronic device 10. The noise may travelback-and-forth between the transmitter and receiver components (e.g.,the antenna). In particular, an antenna uplink power (e.g., aggressor)to adjust and uplink signal strength of RF signals transmitted from theantenna may couple to nonlinear display circuitry (e.g., multiplexercircuits) of the display substrate. Any noise from the transmitted RFsignal may be modulated with baseband frequency from the displaycircuitry. As such, the modulated noise may fall into a downlinkfrequency range (e.g., lower range than the frequency band fortransmitting RF signals). This downlink frequency range may include thefrequency band or range used to receive signals by the receiver of theelectronic device 10. The modulated noise may propagate in abidirectional manner, traveling from the antenna during transmission andthen coupling back to the antenna and interfering with received signals.The bidirectional modulated noise may cause desensitization of thereceiver (e.g., victim).

To facilitate wireless transmissions while mitigating noise, in someembodiments, electromagnetic band gap (EBG) structures may be etchedinto or mounted on and across the support plate (e.g., mid-supportplate) to create a stopband for surface current flowing across thesupport plate. Briefly, EBG structures are structures that may create astopband to block electromagnetic waves of certain frequency bands byforming a pattern of small metal slots or holes on dielectricsubstrates. Moreover, EBG structures that are etched or cut into themid-support plate may be referred to as defected ground structures (DGS)that defect a ground plane and disturb a transmission line. Thus, thesestructures may be used to suppress electromagnetic noise, such as thesurface current or noise that may occur on the support plate andotherwise interfere with intended wireless signals. Moreover, the EBG orDGS structures may be formed such that they do not compromise themechanical support provided by the mid-support plate.

As will be discussed in detail herein, the etched EBG structures may betuned to minimize surface current flow or other noise occurring at aparticular frequency or range of frequencies. For example, the EBGstructures may be used to avert the surface current occurring at aparticular frequency, thereby mitigating unwanted surface currentflowing from one side of the device, such as the side with the noisecausing component, to the other side, such as the side with the antennaused for transmitting or receiving RF signals. Although the followingdescriptions describe noise or surface current as propagating in asingle direction, which represents a particular embodiment, theimplementations of the modified mid-support plate 54A-L may be used tomitigate noise or surface current propagating in multiple directions(e.g., bidirectional propagation).

To mitigate the noise caused by the surface current that may interferewith wireless communication signals, FIG. 5 depicts a modifiedmid-support plate 54A with an EBG barrier 67A of EBG structures 65etched into the modified mid-support plate 54A to avert theelectromagnetic field on the modified mid-support plate 54A, therebymitigating, decreasing, or stopping propagation of the surface current60. The EBG barrier 67A may include a pattern of repeating EBGstructures 65, such that the number of EBG structures 65 included in theEBG barrier 67A may be based on and modified to completely extend acrossand up to the edges of the modified mid-support plate 54A. In thismanner, the EBG structures 65 of the EBG barrier 67A may mitigate ordecrease surface current 60 flow while upholding the structuredcharacteristics of the modified mid-support plate 54A. Although notexplicitly shown, and as previously discussed, the surface current 60may originate from an aggressor component and may flow across the platetowards a victim component. As the surface current 60 flows from theaggressor to the victim, the EBG structures 65 that are across themodified mid-support plate 54A may mitigate or stop the surface current60 from its presently flowing path, such that the surface current 60 maynot significantly pass the EBG barrier 67A.

To further detail the EBG structures 65 that may be used in the patterncreating the EBG barrier 67A to avert the surface current 60 asdescribed in FIG. 5 , diagram of FIG. 6 illustrates narrowband andbroadband EBG structures 65 that may be tuned to particular frequencies.Although the following description describes the EBG structures 65 asslots etched into the modified mid-support plate 54A, which represents aparticular embodiment, the implementations of the modified mid-supportplate 54A using EBG structures 65 may include, but are not limited to,planar EBG structures on the modified mid-support plate 54A, slotted EBGstructures etched into the modified mid-support plate 54A, and/or 3D EBGstructures mounted on top of the modified mid-support plate 54A. Ingeneral, narrowband EBG structures 65 may include one or more straightline-shaped slots without a curve or bend and may be used to tune for anarrowband. On the other hand, broadband EBG structures 65 may includeone or more curved slots that may be used for tuning to broadbandfrequencies. Moreover, a combination of narrowband and broadband slotsmay be used for the EBG structures 65 to facilitate tuning for noiseoccurring on different frequencies.

Narrowband shapes of the EBG structures 65 may include, but are notlimited to, a first narrowband EBG structure 70 and a second narrowbandEBG structure 74. The one or more slots of the EBG structures 65 mayeach be tuned for a narrowband frequency. As shown, the first narrowbandEBG structure 70 includes multiple slots in a cross-like or overlappingpattern. Similarly, the second narrowband EBG structure 74 includesmultiple slots positioned in a parallel and/or perpendicular pattern.The pattern of slots may correspond to a particular narrowband frequencyor range of narrowband frequencies.

However, if wireless applications utilize high data rates, such thatbroadband frequencies are used for the wireless communication, broadbandEBG structures 65 may be used for tuning to broadband frequencies andstopping surface current 60 occurring on the tuned frequencies. By wayof example, an electronic device 10 communicating high bandwidth signalson a range of frequencies (e.g., 2.4 GHz and 5.0 GHz used for Wi-Fi) mayuse broadband EBG shapes etched across and into the modified mid-supportplate 54A to create a barrier. In comparison, if the electronic device10 is communicating data signals on a narrowband, such as the 1.6 GHzused for global positioning system (GPS) communication, narrowband EBGshapes may be used.

In general, the broadband EBG structures 65 may be constructed with oneor more tapered shaped slots. To illustrate, a broadband EBG structure72 shows a round slot along with a rectangular slot. The round slot, andthus a broadband EBG structure 65, may be used to tune for noiseoccurring on a broadband frequencies. In both narrowband and broadbandEBG structures 65, such as the first narrowband EBG structure 70, thesecond narrowband EBG structure 74, and the broadband EBG structure 72,surface current 60 flowing along the modified mid-support plate 54A isconcentrated around the EBG structures 65 of the EBG barrier 67A, whichprevent surface current 60 from further flowing across the aggressor tothe victim on the modified mid-support plate 54A.

In addition to modifying the shape of the EBG structures 65, adjustingthe gap (e.g., width) of the EBG structures 65 etched into the modifiedmid-support plate 54A may allow tuning to a particular range offrequencies. To illustrate, FIG. 7 depicts a graph 80 that indicatesscattering parameter 21 (S-parameter S₂₁) (dB) performance for varyingEBG structure gaps 82. As shown, a 1 millimeter (mm) gap 82A (indicatedby a solid line), a 2 mm gap 82B (indicated by a dashed line), and a 3mm gap 82C (indicated by a bold dashed line) may mitigate, decrease, orstop noise occurring at different frequencies (GHz). For example, the 3mm gap 82C may be the most optimal size if targeting noise occurringbetween 0.8-1 GHz.

To illustrate the implementation of the EBG structure 65 pattern on themodified mid-support plate 54A of FIG. 5 , diagram of FIG. 8 illustratesan EBG slot pattern formed through and across the modified mid-supportplate 54B. The modified mid-support plate 54B may include a first side59 that is adjacent to a display substrate 50 and a second side 61 thatis adjacent to a lower support plate 52. An air gap 58 may exist betweenthe second side 61 and the lower support plate 52, such that surfacecurrent may flow across an electronic device 10 without EBG structures65 on the modified mid-support plate 54B. As illustrated, the EBGstructures 65 may be repeated across and in multiple rows (e.g., two ormore rows) to create an EBG slot barrier 67B. In particular, the EBGstructures 65 of the EBG slot barrier 67B may be etched completelythrough the modified mid-support plate 54B. Although the EBG structures65 are repeated in a non-contiguous manner, such that the EBG structures65 do not touch or share a common edge, which represents a particularembodiment, it should be noted that the methods described herein may beimplemented using EBG structures positioned contiguously.

The rows may be offset from each other to prevent surface current 60from flowing in between the slots. However, dielectric material may beused in the space created by the slots of the EBG slot barrier 67B. Theoffset rows of the slotted EBG structures 65 may maintain the stabilityand structure of the modified mid-support plate 54B. In someembodiments, dielectric material may also be used to maintain thestability of the display 18 structure. Thus, the structure of display 18is functionally or structurally complete or operable while the EBG slotbarrier 67B prevents electromagnetic interference caused by the surfacecurrent 60 that may otherwise flow across the modified mid-support plate54B.

Additionally or alternatively, block diagram of FIG. 9 illustrates animplementation of an EBG three dimensional (3D) barrier 67C across andon the modified mid-support plate 54C. The modified mid-support plate54C may include a first side 59 that is adjacent to a display substrate50 and a second side 61 that is adjacent to a lower support plate 52. Anair gap 58 may exist between the second side 61 and the lower supportplate 52, such that surface current may flow across an electronic device10 without EBG structures 65 on the modified mid-support plate 54C.Similar to the EBG slot barrier 67B, and as illustrated, EBG structures65 of the EBG 3D barrier 67C may be repeated across in one or more rows.In particular, the EBG structures 65 may be mounted onto the modifiedmid-support plate 54C, such that the mounted EBG structures 65 interruptthe transmission line effect created by the air gap 58 of the display 18architecture. In this manner, the air gap 58 is minimized and no longercontinuous, and thus, surface current 60 flowing through the air gap 58may be mitigated or stopped.

Moreover, the 3D nature of the EBG 3D barrier 67C provides additionalstability to the display 18 architecture. However, additionally oralternatively, dielectric material may be used in any remaining spacescreated by the 3D EBG barrier 67C to further maintain the stability ofthe display 18. Thus, the various EBG structure implementations on asupport plate 54, such as the EBG slot barrier 67B or the EBG 3D barrier67C, on the respective modified mid-support plate 54B and 54C, may beused to mitigate or stop surface current 60 from interfering withwireless communications on device 10.

In some implementations, the EBG structures 65 that are etched throughmay vary in shape and size in order to mitigate noise at multiplefrequencies or range of frequencies and/or to accommodate specificdisplay 18 characteristics. As shown in FIG. 10 , multiple patterns ofEBG structures 65 are formed through and across the modified mid-supportplate 54D. Moreover, an RF absorber 66 may be used in addition to or inplace of the multiple EBG structures 65. The RF absorber 66 may includelossy material that attenuates the energy or surface current 60 flowingacross and/or in both directions on the mid-support plate 54D. The lossymaterial may be sheet form and may be strategically placed directly overcircuitry without shorting the circuits. Thus, the RF absorber 66 may beplaced directly over the display circuitry and data lines of the displaysubstrate 50 (not shown), and between the display substrate 50 andmodified mid-support plate 54D. Moreover, the RF absorber 66 may bepositioned in the middle of the modified mid-support plate 54D to absorbthe surface current 60 traveling on the mid-support plate 54, preventingit from reaching victim components.

Additionally or alternatively, the EBG structures 65 may be repeatedacross and in multiple rows to create an EBG slot barrier 67D. Inaddition to the narrowband and broadband EBG shapes previouslydiscussed, the EBG structures 65 may be rectangular, straight line,hairpin shaped, U-shaped, C-shaped, L-shaped, and/or combined shapes.For example, the multiple straight line EBG structures 65 of the EBGslot barrier 67D may be used for tuning to broadband frequencies while aU-shaped EBG structure 65 of a second EBG slot barrier 68A is used fortuning to narrowband frequencies. As such, various EBG shapes may beetched on the modified mid-support plate 54D depending on targetedfrequencies for tuning.

In addition to mitigating noise occurring at particular frequencies, theEBG shape, size, and/or etching location may be selected based on designconstraints, such as mechanical support constraints and wirelesscommunication constraints related to the antenna. For example, the EBGstructures 65 may be placed to avoid the antenna return path when thesurface current 60 travels to and from the antenna in a bidirectionalmanner. If the EBG structures are placed on the antenna return path,then the antenna energy (e.g., from the antenna uplink power) would leakinto the display substrate 50 and couple to components of the displaycircuitry.

In some implementations, the electronic device 10 and/or display 18mechanical characteristics may prevent etching at an optimal location onthe modified mid-support plate 54D. For example, the EBG structures 65may be etched into and across the width 63 (e.g., 85% of the width, 90%of the width, 95% of the width, and so forth) of the modifiedmid-support plate 54D up until the modified mid-support plate 54D nolonger provides structural support. It should be appreciated thatalthough some of the following discussions relate to etching EBGstructures 65 while maintaining the mechanical structure of anelectronic device 10 or display 18, which represents a particularembodiment, the methods and systems may also be performed andimplemented without considering the mechanical support for theelectronic device 10 or display 18. For example, the EBG structures 65may be etched into and all the way across the modified mid-support plate54 to optimally mitigate noise.

To illustrate, FIG. 11 depicts a modified mid-support plate 54E with EBGetching locations that consider electronic device 10 and/or display 18design features. As shown, the modified mid-support plate 54 may includeone or more display flexes 81 that provide physical flexibility (e.g.,bending within a predetermined range) to the mid-support plate 54 and/orsupport regions 83 (e.g., design slot) to accommodate circuitry andcomponents on the lower support plate 52 (not shown). Moreover, themid-support plate 54 may also be designed to accommodate components usedfor modulation. As previously discussed, the uplink power for an RFsignal may generate noise, which may occur at the same RF frequency bandfor transmitting the RF signal. The multiplexer of the multiplexer andde-multiplexer circuitry 84 may modulate the noise with basebandfrequency of the display circuitry. This modulation may result in thenoise occurring at a different frequency band, such as the frequencyband used to receive RF signals. Since the modified mid-support plate54E is designed to support these features, the EBG structure 65 may bestrategically etched in locations that consider these design featuresalong with the goal to mitigate noise, such as the modulated noiseaffecting the receiver.

As shown, the EBG slot barrier 67E may be etched at the same location asthe EBG slot barrier 67D of FIG. 10 since the display flex 81 does notoverlap with the EBG slot barrier 67E location. However, the EBGstructure 65 of the second EBG slot barrier 68B is smaller toaccommodate the adjacent support region 83. As such, depending on thedesign of the electronic device 10 and/or display 18, the etchinglocation and/or EBG structure 65 shape, size, frequency (e.g., multiplerows), and gap 82 (FIG. 7 ) may be adjusted. Moreover, the number of EBGstructures 65 of the EBG slot barrier 67E and the spacing between themmay be based on structural support for the display 18. To furtherillustrate design considerations when selecting EBG structures 65 foretching, the modified mid-support plates 54F-L of FIG. 12 depictdifferent embodiments of the modified mid-support plate 54 that aredesigned to support the stability and mechanical structure of thedisplay 18 while preventing noise that may otherwise flow across themodified mid-support plate 54.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

The techniques presented and claimed herein are referenced and appliedto material objects and concrete examples of a practical nature thatdemonstrably improve the present technical field and, as such, are notabstract, intangible or purely theoretical. Further, if any claimsappended to the end of this specification contain one or more elementsdesignated as “means for [perform]ing [a function] . . . ” or “step for[perform]ing [a function] . . . ,” it is intended that such elements areto be interpreted under 35 U.S.C. 112(f). However, for any claimscontaining elements designated in any other manner, it is intended thatsuch elements are not to be interpreted under 35 U.S.C. 112(f).

The invention claimed is:
 1. A support plate of a display device,having: a first side disposed adjacent to a display substrate of thedisplay device, the first side comprising one or more straightline-shaped electromagnetic band gap structures disposed within thesupport plate and across a width of the display device, the one or morestraight line-shaped electromagnetic band gap structures configured toreduce surface current on the display substrate; and a second sidedisposed adjacent to a conductive plate, the support plate physicallyseparate from the conductive plate.
 2. The support plate of claim 1,wherein the one or more straight line-shaped electromagnetic band gapstructures are configured to reduce the surface current on the displaysubstrate occurring at narrowband frequencies.
 3. The support plate ofclaim 2, wherein the one or more straight line-shaped electromagneticband gap structures are disposed in a cross pattern, an overlappingpattern, or both.
 4. The support plate of claim 2, wherein the one ormore straight line-shaped electromagnetic band gap structures aredisposed in parallel or perpendicularly.
 5. The support plate of claim2, wherein the narrowband frequencies comprise frequencies associatedwith global positioning system (GPS) communications.
 6. The supportplate of claim 1, wherein the one or more straight line-shapedelectromagnetic band gap structures comprise dielectric material.
 7. Thesupport plate of claim 1, wherein the first side comprises one or morecurve-shaped electromagnetic band gap structures disposed within thesupport plate, the one or more curve-shaped electromagnetic band gapstructures configured to reduce surface current on the display substrateoccurring at broadband frequencies.
 8. The support plate of claim 7,wherein the broadband frequencies comprises frequencies between 2.4gigahertz (GHz) and 5.0 GHz.
 9. A display, comprising: a displaysubstrate; a mid-support plate disposed adjacent to the displaysubstrate, the mid-support plate comprising one or more multiple edgedelectromagnetic band gap structures disposed within the mid-supportplate, wherein the one or more multiple edged electromagnetic band gapstructures comprise different edge lengths and edge heights; and a lowersupport plate disposed adjacent to the mid-support plate, the lowersupport plate physically separate from the mid-support plate.
 10. Thedisplay of claim 9, wherein the one or more multiple edgedelectromagnetic band gap structures are disposed across a width of thedisplay.
 11. The display of claim 9, wherein the one or more multipleedged electromagnetic band gap structures are configured to reducesurface current occurring at a first range of broadband frequenciesusing the edge lengths and reduce surface current occurring at a secondrange of broadband frequencies using the edge heights.
 12. The displayof claim 9, wherein the one or more multiple edged electromagnetic bandgap structures comprise one or more bow tie-shaped structures.
 13. Thedisplay of claim 9, wherein the one or more multiple edgedelectromagnetic band gap structures are disposed within a row across themid-support plate to create a contiguous, non-contiguous, or both,barrier across the mid-support plate.
 14. The display of claim 9,wherein the mid-support plate comprises one or more straight line-shapedelectromagnetic band gap structures disposed within the mid-supportplate, the one or more straight line-shaped electromagnetic band gapstructures configured to reduce a surface current flow on the displayoccurring at narrowband frequencies based on a shape of the one or morestraight line-shaped electromagnetic band gap structures.
 15. Thedisplay of claim 9, wherein the mid-support plate comprises one or morecurve-shaped electromagnetic band gap structures disposed within themid-support plate, the one or more curve-shaped electromagnetic band gapstructures configured to reduce a surface current flow on the displayoccurring at broadband frequencies based on a shape of the one or morecurve-shaped electromagnetic band gap structures.
 16. A supportstructure of a display, comprising: a first support plate comprising afirst side configured to be disposed adjacent to a display layer of thedisplay comprising light emitting diodes, one or more electromagneticband gap structures having one or more curved lines to reduce surfacecurrent on the display occurring at broadband frequencies, a secondside; and a second support plate configured to be disposed adjacent tothe second side of the first support plate, the second support platephysically separate from the first support plate.
 17. The supportstructure of claim 16, wherein a first electromagnetic band gapstructure of the one or more electromagnetic band gap structures has afirst dimension and a second electromagnetic band gap structure of theone or more electromagnetic band gap structures has a second dimensiondifferent than the first dimension, wherein the first electromagneticband gap structure and the second electromagnetic band gap structure areconfigured to reduce surface current flow occurring at differentfrequencies based at least in part on the first dimension and the seconddimension.
 18. The support structure of claim 16, wherein the one ormore electromagnetic band gap structures have one or more straight linesconfigured to reduce surface current on the display occurring atnarrowband frequencies.
 19. The support structure of claim 16, wherein awidth of each of the one or more electromagnetic band gap structures isconfigured to reduce surface current flow having a particular frequency.20. The support structure of claim 19, wherein the width comprisesbetween 1 millimeter and 3 millimeters.